1. Clinical Overview
Cefotaxime is a third-generation, broad-spectrum, bactericidal cephalosporin antibiotic. It is highly effective against Gram-negative bacteria, including many beta-lactamase-producing strains, while retaining significant activity against Gram-positive organisms. It is a cornerstone of empirical therapy for serious hospital-acquired infections in India, particularly in ICU settings, due to its stability against many plasmid-mediated beta-lactamases.
| Onset | Duration | Bioavailability |
|---|---|---|
| Peak serum concentrations are achieved within 30 minutes of an intravenous (IV) or intramuscular (IM) injection. | The dosing interval is typically 6-12 hours for most infections, depending on severity, due to its post-antibiotic effect and time-dependent killing. | Approximately 90-95% following IV administration. IM bioavailability is nearly 100% but absorption is slightly delayed. |
2. Mechanism of Action
Cefotaxime is a bactericidal beta-lactam antibiotic. It inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs) located inside the bacterial cell wall. This binding inhibits the final transpeptidation step of peptidoglycan synthesis, leading to the formation of a defective cell wall and ultimately to osmotic lysis and cell death.
3. Indications & Uses
- Severe Lower Respiratory Tract Infections (Pneumonia, Lung Abscess)
- Complicated Urinary Tract Infections (Pyelonephritis)
- Intra-abdominal Infections (Peritonitis, Cholangitis)
- Bacterial Septicaemia
- Skin and Soft Tissue Infections
- Bone and Joint Infections
- Gonorrhoea (as a single-dose therapy)
- Meningitis (especially in neonates and children; off-label in adults where 3rd gen cephalosporins are indicated)
4. Dosage & Administration
Adult Dosage: Moderate infections: 1gm IV/IM every 12 hours. Severe infections: 1-2gm IV every 6-8 hours. Life-threatening infections (e.g., meningitis, septic shock): Up to 2gm IV every 4 hours.
Administration: IV: Reconstitute 1gm vial with 10 mL Water for Injection. For IV bolus, administer over 3-5 minutes. For IV infusion, further dilute in 50-100 mL of compatible fluid (NS, D5W, RL) and infuse over 20-30 minutes. IM: Reconstitute with 2-3 mL of Water for Injection or 1% Lidocaine HCl (without epinephrine) to reduce pain. Inject deep into a large muscle mass. Solutions are light yellow; discard if discolored or contains particulate matter.
5. Side Effects
Common side effects may include:
- Pain/Induration at IM injection site
- Phlebitis/Thrombophlebitis at IV site
- Diarrhoea (may be Clostridium difficile-associated)
- Rash, Pruritus
- Eosinophilia
- Transient elevation of liver enzymes (ALT, AST)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Probenecid | Inhibits renal tubular secretion of cefotaxime, increasing and prolonging serum levels. | Moderate |
| Aminoglycosides (e.g., Gentamicin, Amikacin) | Synergistic antibacterial effect against some organisms (e.g., Pseudomonas). Increased risk of nephrotoxicity. | Moderate |
| Potent Diuretics (e.g., Furosemide) | May increase the risk of nephrotoxicity. | Moderate |
| Oral Anticoagulants (Warfarin) | May potentiate anticoagulant effect, increasing risk of bleeding. | Major |
| Chloramphenicol | Antagonistic antibacterial effect; avoid concomitant use. | Major |
7. Patient Counselling
- Complete the full prescribed course even if you feel better.
- Inform all your doctors about any allergy to penicillin or other drugs.
- Do not share your medicine with anyone else.
- Inform your doctor if you are pregnant, planning pregnancy, or breastfeeding.
- For IM injection, report severe pain at the injection site.
8. Toxicology & Storage
Overdose: Symptoms of overdose are primarily neurological, including seizures, encephalopathy, and neuromuscular excitability. Nausea, vomiting, and diarrhoea may also occur.
Storage: Store unopened vials at controlled room temperature (15-25°C), protected from light and moisture. After reconstitution: For IV use, the solution in NS or D5W is stable for 24 hours at room temperature or 10 days if refrigerated (2-8°C). For IM use, use immediately after reconstitution. Do not freeze. Keep out of reach of children.